Armor of Agathys or Mirror Image? [Bladelock]

[zeek0]

Since a warlock only gets a few spells at a time, it seems reasonable to only carry a single defensive spell.

For a Fiend Pact bladelock Armor of Agathys is the obvious choice, since getting hit can be beneficial. But what about for a GOO or Fey Pact?

[GiantOctopodes]

Armor of Agathys underwhelms me at low levels, as it prevents at most 5 damage, and unless the attack in question deals less than 5 damage, it only deals 5 damage. That damage is also predicated on it being a melee attack, vs a ranged attack or spell, which deals the 5 damage to you to negate those temp HP. However, it does scale well, and it has the benefit of being able to be "pre-cast" when going into a dangerous situation, whereas mirror image's duration is too short to generally support that.

For Mirror image, there is no limit on the number of attacks it can turn aside, though generally if that number is more than 3, the attacks would have been turned aside by your own AC anyway. Those 3 attacks are likely to be dealing anywhere from 15-21 damage all told. It also doesn't scale at all.

Everything considered, I would say mirror image is better up until you get 4th level spell slots, at which point Armor of Agathys is better. Up until you gain at least 2nd level slots, and possibly 3rd level slots, mirror image is potentially better for a bladelock as well.

tl;dr: Start with mirror image, then switch it out for Armor of Agathys once you reach higher level slots.

[ghost_warlock]

Armor of Agathys underwhelms me at low levels, as it prevents at most 5 damage, and unless the attack in question deals less than 5 damage, it only deals 5 damage. That damage is also predicated on it being a melee attack, vs a ranged attack or spell, which deals the 5 damage to you to negate those temp HP. However, it does scale well, and it has the benefit of being able to be "pre-cast" when going into a dangerous situation, whereas mirror image's duration is too short to generally support that.

For Mirror image, there is no limit on the number of attacks it can turn aside, though generally if that number is more than 3, the attacks would have been turned aside by your own AC anyway. Those 3 attacks are likely to be dealing anywhere from 15-21 damage all told. It also doesn't scale at all.

Everything considered, I would say mirror image is better up until you get 4th level spell slots, at which point Armor of Agathys is better. Up until you gain at least 2nd level slots, and possibly 3rd level slots, mirror image is potentially better for a bladelock as well.

tl;dr: Start with mirror image, then switch it out for Armor of Agathys once you reach higher level slots.

Mirror image is a 2nd-level spell.

[odigity]

Mirror image is a 2nd-level spell.

At first level you only have one slot, and are spending it on Hex, so it doesn't matter.
At second level you get a second slot, but still limited to 1st level spells, so sure, Armor of Agathys is an acceptable choice. (I prefer Hellish Rebuke.)
At third level you get second level spells/spell slots, so you can swap out Armor for Mirror Image if you prefer the latter and only one want to know one defense spell.
Later you swap MI back out for AoA again if you take the advice of the other posted in this thread who thinks AoA trumps MI after a certain point.

I see no problems here.